The present invention relates to field of inclinable three-wheeled vehicles, such as scooters, having two front steered wheels parallel to each other and inclinable with respect to the ground, with the chassis.
These vehicles combine the easy handling of a scooter with the safety afforded by better adhesion to the ground and the stability resulting from a means that does not exist on a two-wheeler.
Numerous solutions with motorised machines with two twin front wheels are known in the prior art.
By way of example, the international application WO03057549 describes a set of orientable wheels with induced inclination, which has a pair of parallel wheel hub carriers, placed on each side of an inclinable chassis edge. A system of articulated triangular bars and a transmission connect the wheel hub carriers to the chassis edge, so that the wheels incline while remaining parallel to the chassis on bends in unison with the chassis edge. A steering mechanism couples the wheel hub carriers to the chassis edge, so that an inclination induced on the chassis edge directs the wheel hub carriers at a steering angle that depends on the angle of the inclination induced.
European patent application EP0251906 describes a stabilising device for an inclinable vehicle formed by a deformable primary part connected to the ground, in which a carrier element turns about an element when the vehicle tilts, and a carried element connected to a secondary part movable with respect to the primary part is raised during this inclination by virtue of a rotation multiplying system acting on a carrier arm, so that the centre of gravity G of the whole of the vehicle is itself raised during such an inclination movement, which ensures stability of the vehicle.
The international application WO2011005945 describes another example of an inclinable vehicle comprising a chassis that pivots with respect to a chassis element pivoting about a pivot axis. A torque exerted on a steering assembly in a first direction causes the chassis to pivot with respect to the chassis element pivoting in an opposite second direction at least when the speed of the vehicle is greater than a first threshold speed in order to steer the vehicle in the second direction. An actuator urges the chassis in the direction of a vertical position when the chassis is in an inclined position and a speed of the vehicle is below a second threshold value. The invention also concerns a method according to which a torque is exerted on the chassis in the direction opposite to the steering torque when the speed is above the first threshold speed. The torque exerted by the actuator is opposite to the angle of inclination when the speed of movement is below the second threshold speed.
The international application WO2007127783 describes a vehicle that comprises vehicle bodywork and a vehicle support assembly. The bodywork of the vehicle has a longitudinal axis and is configured so as to carry a rider on it. The support assembly comprises first and second inclinable wheels each disposed at a different lateral location with respect to the longitudinal axis, an inclination mechanism associating the bodywork of the vehicle while supporting it from inclinable wheels in order to enable the bodywork of the vehicle to incline in a first inclination range with respect to the surface on which the inclinable wheels are disposed and an inclination limiter associated functionally with the inclination mechanism in order to limit the inclination of the bodywork of the vehicle to a value below the first inclination range, a limiter that can be deactivated in order to allow an inclination throughout the first inclination range.
The international application WO2005051689 relates to a vehicle chassis with a tilting system, which comprises a differential gearing driving opposed half-shafts. Each half-shaft is connected to a respective wheel hub. Pivoting connection links are provided between the chassis and the hubs; and a control arm, provided between the chassis and the axle head, limits the movement thereof. This device constitutes a novel vehicle design with a tilting system provided with a shaft transmission and a low centre of gravity.
The international application WO2005002957 relates to a three-wheeled vehicle, which comprises a chassis with an engine, driving gears and at least one driven wheel at the rear, and two front wheels used partly to steer the vehicle. This vehicle may also be steered so that the chassis with the engine, the driving gears and the driven rear wheel can be inclined to the side in order to turn like a motorcycle. This invention relates in particular to a vehicle design that contributes to the moving of the centre of gravity, when such a vehicle is inclined to the side, so that it is in particular easier to straighten it up. This invention also makes it possible to modify and determine the driving characteristics of the vehicle by varying various design parameters, while remaining within the field covered by the present invention. This invention also relates to a special design for mounting footrests on which the rider of the vehicle can place his feet while driving the vehicle. This special design actively contributes to modifying the geometry between footrests and the vehicle chassis when the vehicle is used and in particular when it is inclined to the side in order to turn.
The American U.S. Pat. No. 7,530,419 describes another example of a three-wheeled vehicle, consisting of a chassis with an engine, driving gears and at least one driven wheel at the rear, and two front wheels used partly to steer the vehicle. This vehicle may also be steered so that the chassis with the engine, the driving gears and the driven rear wheel can be inclined to the side in order to turn like a motorcycle. This invention relates in particular to a vehicle design that contributes to the moving of the centre of gravity, when such a vehicle is inclined to the side, so that it is in particular easier to straighten it up. This invention also makes it possible to modify and determine the driving characteristics of the vehicle by varying various design parameters, while remaining within the field covered by the present invention.
The American patent application US20110215544 describes a variant of a three-wheeled vehicle, a left wheel having a first rotation shaft, the right wheel coupled mechanically to the base on the left-hand side of the longitudinal axis with a left-hand independent suspension mechanism that urges the left wheel against the road over a range of vertical movement of the left wheel, a first left-hand mechanism dimension varying in response to the vertical movement of the left wheel. The right wheel having a second rotation axis, the right wheel coupled mechanically to the base on the right of the longitudinal axis with a right independent suspension mechanism that urges the right wheel against the road over a range of vertical movement of the right wheel, a second dimension of the right-hand mechanism varying in response to the vertical movement of the right wheel.
The American U.S. Pat. No. 7,648,148 describes a vehicle comprising a chassis having a front part and a rear part. A pivoting chassis element is connected pivotally to the chassis about a roughly horizontal pivot axis. The chassis can pivot with respect to the frame element and can pivot between a vertical position and a plurality of sloping positions. The steering assembly is supported by the frame in order to steer the vehicle. An actuation device has a first part connected to the chassis and a second part connected to the pivoting element of the chassis. The actuator functions so as to selectively pivot the frame with respect to a reference angle about the pivot axis. The method comprises: determining a steering torque exerted on the steering assembly, determining a speed of movement of the vehicle, determining an angle of inclination of the mount with respect to the pivoting element of the chassis, and exerting a torque about the pivot axis in a first direction using the actuator in response to a steering torque exerted on the steering assembly in a second direction opposite to the first direction when the speed of movement is greater than a threshold speed, which causes the vehicle to turn in the first direction.
The American U.S. Pat. No. 8,419,027 describes another steering system for a vehicle comprising a frame having a steering tube, a control rod extending rotatably through the steering tube, an inclinable unit disposed on the steering tube, two suspension units connected to and disposed partially under the inclinable unit, and two front wheels connected respectively to the suspension units. The inclinable unit comprises two lateral tubes flanking the steering tube. The suspension units extend respectively in the two lateral tubes.
The solutions of the prior art have a first drawback relating to the control of the inclination at rest. In this case, no centrifugal force compensates for the transverse component, and the weight of the machine has a tendency to amplify the inclination as soon as it commences to lean.
When the machine is heavy, controlling it at rest or during manoeuvres at very low speed may prove to be a problem, in particular for a novice who is not very muscular. The weight of some machines exceeds 200 kg, and it then becomes very difficult to prevent the machine from tilting and falling when the inclination inadvertently exceeds a significant angle. Lifting the machine again is then sometimes quite simply impossible for a person without help.
A second drawback concerns the weight of the mechanisms used for articulating the front wheels. This weight constitutes an unsprung weight detrimental to the dynamic qualities and comfort of the machine.
These weights may also be detrimental to the performance (consumption, acceleration, maximum speed) of a machine when the engine is of low capacity, for example 50 cm2.